The quantity of information or data that is indicated to a driver because of the increasing number of convenience devices, such as navigational devices, telecommunications devices, driver assistance systems and desired warning indications, etc., is increasing steadily. In many vehicles, therefore, so-called multi-function operating devices are already being installed which, for example, are situated in the center console. In the case of this arrangement, in order to receive the information, the driver is forced to avert his view from the traffic happenings. For this reason, it may be of advantage to indicate at least a portion of the data in the instrument cluster that is located in the driving direction, in the field of view of the vehicle's driver. In that case, the problem may arise that only a certain indicating area in the instrument cluster is available, besides the analog display elements for vehicle speed, rotary engine speed, etc.
For this reason, people are working on new concepts, for instrument clusters, which are able to reproduce a larger quantity of data, without having to do without the usual analog display instruments.
A display device is described in European Published Patent Application No. 0 482 805, in which a first and a second image source are provided. The imaging illumination of the first image source is reflected to the observer by a planar combining device and two additional mirrors located in the beam path of the reflected light.
The image-forming illumination of the second image source is, in this context, transmitted by the combining device, and is then also reflected to the observer by the two mirrors. In this context, the first image source may have a group of electromechanical display devices, such as of speed, oil pressure, tank level, and, for example, display lights, such as directional signals, high beam and emergency indicators. The second image source is a liquid crystal display for making available alphanumeric data, such as messages, maintenance instructions and settings for the environment. In conventional display device, neither of the two image sources is in the direct field of view of the driver, so that a purely virtual image is created. Furthermore, it may be difficult to get a grip on the parallaxes created by the differently situated image sources and the multiple reflections of the image-forming light of the image sources, such that no image distortions are created.
Moreover, Japanese Published Patent Application No. 2002-79848 describes an instrument cluster for a motor vehicle having a conventional electromechanical display device, in whose display image, via a concave, semitransparent mirror, which is designed to let through the image-forming light of the electromechanical display device, a virtual image of a display device, that is not situated in the field of view of the driver, is reflected in. With the aid of this display device, however, one is not able to solve the problem, compared to conventional display devices, of showing, in a manner that is quickly assimilated, a larger quantity of different data to the driver, since space has to be provided in the electromechanical display device for the reflected image of the display device.